1. Priority Claim
This application claims the benefit of priority from European Patent Application No. 06014390.6, filed Jul. 11, 2006, which is incorporated by reference. 
1. Technical Field
The invention relates to digital radio, and in particular, to decoding a digital radio stream.
2. Related Art
Digital radio broadcasting has become more popular because of its availability and superior audio quality compared to traditional analog radio broadcasting. Digital radio broadcasting may include transmission and reception of digital radio streams on existing radio frequency bands, such as Amplitude Modulation (AM) and Frequency Modulation (FM). Digital radio may utilize compression and modulation of audio and data to more effectively take advantage of the bandwidth of AM and FM frequencies. A digital radio stream may include several channels that contain audio, informational data, diagnostic parameters, and other data. For example, the Digital Radio Mondiale (DRM) standard may be broadcast at AM radio bands below 30 MHz. A DRM digital radio stream may include three channels: a Main Service Channel (MSC), a Fast Access Channel (FAC), and a Service Description Channel (SDC).
The MSC channel may contain the data for the DRM services. The MSC channel may contain audio or informational data, depending on the type of service being broadcast. The FAC channel may contain transmission frames that describe the type of services broadcast on the MSC channel. The FAC channel may contain information on the type of modulation, number of services, type of services, and other information to inform a DRM receiver on how to decode the MSC channel. The SDC channel may contain information about a received DRM digital radio stream, such as a radio station identifier, geographic location, time, date, and other information.
Because the MSC channel may contain a large amount of data compressed using a complex compression algorithm, the decoding latency time of the MSC channel may be much greater than the decoding latency time of the FAC and SDC channels. When a user tunes to a new DRM digital radio stream, existing DRM receivers may take time to decode the MSC channel, which may lead to a long delay to hear the audio that is contained in the MSC channel. Moreover, while an existing DRM receiver may simultaneously decode the FAC and SDC channels during MSC channel decoding, such a receiver may not output the data contained in the FAC and SDC channels until the MSC channel decoding is finished. This may result in an unsatisfactory user experience due to the high decoding latency time for the MSC channel. Therefore, a need exists for a system of decoding a digital radio stream with multiple channels to provide a more satisfactory user experience by outputting at least part of the digital radio stream before all the channels are finished decoding.